Lens shutter mechanism

ABSTRACT

A lens shutter mechanism includes, between front and rear support frames having photographing apertures, shutter sectors which open and close the photographing apertures; a shutter drive ring which is rotatable about the optical axis to drive the shutter sectors; diaphragm sectors which change an aperture diameter of the photographing apertures independently of the shutter sectors; and a diaphragm drive ring which is rotatable about the optical axis to drive the diaphragm sectors. The shutter drive ring and the diaphragm drive ring are located at different radial positions and at the same optical axis position. One and the other of the shutter drive ring and the diaphragm drive ring is provided with an inner flange and an outer flange respectively, which radically project toward each other so as to overlap in the axial direction, and engage so as to be relatively slidable in the circumferential direction.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a lens shutter mechanism.

[0003] 2. Description of the Related Art

[0004] In a known lens shutter mechanism for opening and closing a photographing aperture, provided in a compact camera or the like, in general, the shutter mechanism is supported between front and rear support frames that are spaced apart in the optical axis direction. The lens shutter mechanism includes light intercepting members (sectors or blades), which are moved into and retracted from the photographing aperture, and a drive ring which drives the light intercepting members.

[0005] It is necessary to prevent leakage of harmful light from the periphery of the shutter mechanism toward the outer peripheral side of the support frames. In an arrangement in which drive force is transmitted from outside the support frames to the drive ring, an opening is formed on the outer peripheral portion of the support frames to transmit the drive force. This opening makes it difficult to intercept light completely. In a known light interception device for a lens-shutter unit, light interception tapes are attached or adhered to the outer peripheries of the support frames. However, there is a chance that the adhesive of the light interception tape sticks to the light interception members or the drive ring, etc., thus resulting in failure of correct operation thereof.

[0006] Moreover, in a known lens shutter mechanism in which a shutter and a diaphragm are provided adjacent to each other in the optical axial direction, the two separate light intercepting members provided in the support frames increase the number of movable members. Consequently, the adhesion of the light interception tapes without interfering with the operation of the movable members is more difficult.

[0007] Furthermore, a rotation support portion of the drive ring is supported by a support frame. If the shutter drive ring and the diaphragm drive ring are separately provided, the support structure of the respective drive rings is complicated, thus resulting in an increase in the size of the lens shutter mechanism.

SUMMARY OF THE INVENTION

[0008] The present invention provides a simple and small lens shutter mechanism in which the surrounding components of a shutter can be reliably intercepted from harmful light.

[0009] For example, in an embodiment, a lens shutter mechanism includes, between front and rear support frames spaced in an optical axis direction and having photographing apertures, shutter sectors which open and close the photographing apertures, a shutter drive ring which is rotatable about the optical axis to drive the shutter sectors, diaphragm sectors which change an aperture diameter of the photographing apertures independently of the shutter sectors, and a diaphragm drive ring which is rotatable about the optical axis to drive the diaphragm sectors. The shutter drive ring and the diaphragm drive ring are located at different radial positions and at the same position in the optical axis direction. One and the other of the shutter drive ring and the diaphragm drive ring is provided with an inner flange and an outer flange respectively, the inner flange and the outer flange projecting in a radial direction toward each other so as to overlap in the axial direction, and engaging so as to be relatively slidable in the circumferential direction.

[0010] An axial position of one of the shutter drive ring and diaphragm drive ring can be determined in accordance with an engagement thereof with the front and rear support frames. An axial position of the other of the shutter drive ring and diaphragm drive ring can determined in accordance with an engagement thereof with one of the front and rear support frames and in accordance with an engagement thereof between the inner flange and the outer flange.

[0011] The lens shutter mechanism can further include an opening between the front and rear support frames, which extends form the inner diameter side to the outer diameter side of the front and rear support frames. One of the shutter drive ring and the diaphragm drive ring, which is positioned at an outer radial position with respect to the other of the shutter drive ring and the diaphragm drive ring, can be provided with a fitting portion which is fitted in the opening in order to cover the opening, the fitting portion being movable in the circumferential direction.

[0012] One of the front and rear support frames can be provided on the outer peripheral edge thereof with an outer peripheral wall portion which projects in the optical axis direction close to the other of the front and rear support frames. The one of the shutter drive ring and the diaphragm drive ring, having the fitting portion, partly overlaps the outer peripheral wall portion in the radial direction to cover the opening together with the outer peripheral wall portion.

[0013] The lens shutter mechanism can further include a driven projection provided on the fitting portion of the one of the shutter drive ring and the diaphragm drive ring, the driven projection extending outwardly from the opening in the radial direction; and a rotational force providing device provided outside the front and rear support frames, which engages with the driven projection to cause the one of the shutter drive ring and the diaphragm drive ring to rotate.

[0014] The lens shutter mechanism can be provided in a zoom lens, and the rotational force providing device can provide rotation to the driven projection in accordance with a zooming operation of the zoom lens to thereby rotate the one of the shutter drive ring and the diaphragm drive ring which includes the driven projection.

[0015] One of the front and rear support frames can be provided with a motor drive gear which projects from a surface thereof opposed to the other of the front and rear support frames, the motor drive gear being driven by a motor. The other of the shutter drive ring and the diaphragm shutter drive ring, which is positioned at an inner radial position, is provided on the outer peripheral surface thereof with a gear which engages with the motor drive gear. A radial space in which the motor drive gear is accommodated can be provided between the shutter drive ring and the diaphragm drive ring.

[0016] The motor can be controlled by a controller, to change the angular displacement and the rotation speed of the drive ring having the gear which engages with the motor drive gear.

[0017] The diaphragm drive ring can be located at an outer radial position with respect to the shutter drive ring, the diaphragm drive ring being provided with the inner flange on an inner peripheral surface thereof, and the shutter drive ring being provided with the outer flange on an outer peripheral surface thereof.

[0018] In another embodiment, a lens shutter mechanism includes, between front and rear support frames spaced in an optical axis direction and having photographing apertures, shutter sectors which open and close the photographing apertures, a shutter drive ring which is rotated about the optical axis to drive the shutter sectors, diaphragm sectors which change an aperture diameter of the photographing apertures independently of the shutter sectors, and a diaphragm drive ring which is rotated about the optical axis to drive the diaphragm sectors. The shutter drive ring and the diaphragm drive ring are located at different radial positions and at the same position in the optical axis direction, so that the shutter drive ring is located at an inner radial position and the diaphragm drive ring is located at an outer radial position. The diaphragm drive ring is provided with an inner flange which projects inwardly in the radial direction, and the shutter drive ring is provided with an outer flange which projects outwardly in the radial direction, the inner flange and the outer flange overlapping in the axial direction and engaging so as to be relatively slidable in the circumferential direction.

[0019] An axial position of the diaphragm drive ring can be determined in accordance with an engagement thereof with the front and rear support frames. An axial position of the shutter drive ring can be determined in accordance with an engagement thereof with one of the front and rear support frames and in accordance with an engagement thereof between the inner flange and the outer flange.

[0020] The lens shutter mechanism can further include an opening between the front and rear support frames, which extends form the inner diameter side to the outer diameter side of the front and rear support frames. The diaphragm drive ring can be provided with a fitting portion which is fitted in the opening in order to cover the opening, the fitting portion being movable in the circumferential direction.

[0021] One of the front and rear support frames can be provided on the outer peripheral edge thereof with an outer peripheral wall portion which projects in the optical axis direction close to the other of the front and rear support frames. The diaphragm drive ring partly overlaps the outer peripheral wall portion in the radial direction to cover the opening together with the outer peripheral wall portion.

[0022] The lens shutter mechanism can further include a driven projection provided on the fitting portion of the diaphragm drive ring, the driven projection extending outwardly from the opening in a radial direction; and a rotational force providing device provided outside the front and rear support frames, which engages with the driven projection to cause the diaphragm drive ring to rotate.

[0023] The lens shutter mechanism can be provided in a zoom lens, and the rotational force providing device can provide rotation to the driven projection in accordance with a zooming operation of the zoom lens to thereby rotate the diaphragm drive ring.

[0024] One of the front and rear support frames can be provided with a motor drive gear which projects from a surface thereof opposed to the other of the front and rear support frames, the motor drive gear being driven by a motor. The shutter drive ring can be provided on the outer peripheral surface thereof with a gear which engages with the motor drive gear. A radial space in which the motor drive gear is accommodated can be provided between the shutter drive ring and the diaphragm drive ring.

[0025] The motor can be controlled by a controller, to change the angular displacement and the rotation speed of the shutter drive ring.

[0026] The present disclosure relates to subject matter contained in Japanese Patent Application No. 2001-81608 (filed on Mar. 21, 2001) which is expressly incorporated herein by reference in its entirety.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The invention will be discussed below with reference to the accompanying drawings, in which:

[0028]FIG. 1 is an exploded perspective view of components of a zoom lens barrel, according to the present invention;

[0029]FIG. 2 is a sectional view of an upper half of the zoom lens barrel in a retracted position;

[0030]FIG. 3 is a sectional view of an upper half of the zoom lens barrel in a wide-angle position;

[0031]FIG. 4 is a sectional view of an upper half of the zoom lens barrel in a telephoto position;

[0032]FIG. 5 is a perspective view of the zoom lens barrel in an advanced position;

[0033]FIG. 6 is an exploded perspective view of the zoom lens barrel shown in FIG. 5;

[0034]FIG. 7 is an exploded perspective view of the zoom lens barrel, showing a more detailed disassembly than FIG. 6;

[0035]FIG. 8 is a perspective view of first and second outer barrels;

[0036]FIG. 9 is a perspective view of a third linear guide ring;

[0037]FIG. 10 is an exploded perspective view of a third linear guide ring and a lens-shutter unit;

[0038]FIG. 11 is a developed view of a third linear guide ring, showing a diaphragm control cam groove thereof;

[0039]FIG. 12 is a developed view of an inner surface of a cam ring, showing a cam groove profile, by way of example;

[0040]FIG. 13 is an exploded perspective view of a lens-shutter unit;

[0041]FIG. 14 is an exploded perspective view of a rear unit of a lens-shutter unit;

[0042]FIG. 15 is a sectional view of an upper half of a rear unit of a lens-shutter unit;

[0043]FIG. 16 is a perspective view of a front unit of a lens-shutter unit and a lens-shutter unit FPC (annular FPC);

[0044]FIG. 17 is an exploded perspective view of a front holder ring and an annular FPC;

[0045]FIG. 18 is an exploded rear perspective view of a front unit and a rear unit, of a lens-shutter unit;

[0046]FIG. 19 is a rear perspective view of an assembly of a front and rear unit, of a lens-shutter unit;

[0047]FIG. 20 is an exploded perspective view of a first variable power lens group and surrounding components thereof;

[0048]FIG. 21 is an exploded perspective view of a lens-shutter unit and a lens support barrel;

[0049]FIG. 22 is an enlarged developed view of a front sub-lens group frame, a rear sub-lens group frame and a drive ring, in connection with a front hold ring;

[0050]FIG. 23 is an explanatory view showing a focusing operation using a drive ring;

[0051]FIG. 24 is an enlarged sectional view of an upper half of a lens-shutter unit and the surrounding components thereof when a lens barrier thereof is closed;

[0052]FIG. 25 is a sectional view similar to FIG. 24, when a lens barrier is open;

[0053]FIG. 26 is a block diagram of a control system of a zoom lens barrel shown in FIGS. 2 through 4;

[0054]FIG. 27 is a sectional view of an upper half of a rear unit, taken in a position different from that of FIG. 15.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0055] The following embodiments are addressed to a lens shutter mechanism applied to a zoom lens barrel. The structure of the zoom lens barrel is discussed first, and is followed by an explanation of a lens shutter mechanism.

[0056] As shown in FIG. 1, a stationary barrel 12 secured to a camera body 11 is provided on its inner peripheral surface with a female helicoid 12 a which is screw-engaged with a male helicoid 14 a formed on an outer peripheral surface of a first helicoid ring 14. A pinion 16 which is rotated by a zooming motor 15 is provided outside the stationary barrel 12. The pinion 16 is in mesh with a gear 14 b formed on the outer peripheral surface of the first helicoid ring 14 via a cut-out portion of the male helicoid 14 a. The gear 14 b is inclined in the same direction as the lead of the male helicoid 14 a. The first helicoid ring 14 is connected at the front end thereof to a first outer barrel 17. Consequently, when the first helicoid ring 14 is rotated in the forward or reverse direction by the zooming motor 15, the first helicoid ring 14 and the first outer barrel 17, integrally connected thereto, are moved in the optical axis direction in accordance with the engagement of the female helicoid 12 and the male helicoid 14 a.

[0057] A first linear guide ring 18 which is rotatable relative to, and movable together with, the first outer barrel 17 in the optical axis direction (i.e., not relatively movable with respect to the first outer barrel 17 in the optical axis direction) is supported in the inner periphery of the first outer barrel 17. The first linear guide ring 18 has a projection 18 a which is engaged in a linear guide groove 12 b of the stationary barrel 12, so that the first linear guide ring 18 is linearly movable only in the optical axis direction. The axial displacement of the first linear guide ring 18 is detected by a brush 19 and a code plate 20 secured to the first linear guide ring 18 and the stationary barrel 12, respectively.

[0058] The first linear guide ring 18 is provided on the inner peripheral surface thereof with a female helicoid 18 b which is engaged with a male helicoid 21 a formed on an outer peripheral surface of a second helicoid ring 21. The second helicoid ring 21 is provided on the outer peripheral surface thereof with a pair of guide portions 21 b which are engaged in guide grooves 17 a (see FIG. 8) formed in the inner peripheral surface of the first outer barrel 17 through guide through-grooves 18 c formed in the first linear guide ring 18. The guide through-grooves 18 c are elongated through-holes inclined in the same direction as the female helicoid 18 b, and the guide grooves 17 a are linear grooves parallel with the optical axis O of the zoom lens system. The second helicoid ring 21 is connected at the front end thereof to a second outer barrel 23. Consequently, when the first outer barrel 17 is rotated in the forward or reverse direction by the zooming motor 15, the second helicoid ring 21 and the second outer barrel 23, integrally connected thereto, are rotated in accordance with the engagement between the guide portion grooves 17 a and the guide portions 21 b, and accordingly, are moved in the optical axis direction with respect to the first linear guide ring 18 (and an assembly of the first outer barrel 17 and the first helicoid ring 14) in accordance with the female helicoid 18 b and the male helicoid 21 a.

[0059] A second linear guide ring 25 which is rotatable relative to, and is movable in the optical axis direction together with, the second outer barrel 23 (i.e., not movable in the optical axis direction relative to the second outer barrel 23) is supported in the second outer barrel 23. The second linear guide ring 25 has a projection 25 a which is engaged in a linear guide groove 18 d of the first linear guide ring 18, so that the second linear guide ring 25 is linearly movable only in the optical axis direction.

[0060] Similar to the first linear guide ring 18, the second linear guide ring 25 is provided on the inner peripheral surface thereof with a female helicoid 25 b which is engaged with a male helicoid 30 a formed on an outer peripheral surface of a rear end of a cam ring (third outer barrel) 30. The cam ring 30 is provided on the outer peripheral surface thereof with a pair of guide portions 30 b which are engaged in guide grooves 23 a (see FIG. 8) formed in the inner peripheral surface of the second outer barrel 23 through guide through-grooves 25 c formed in the second linear guide ring 25. The guide through-grooves 25 c are in the form of elongated through-holes inclined in the same direction as the female helicoid 25 b, and the guide grooves 23 a are in the form of linear grooves parallel with the optical axis O. Consequently, when the second outer barrel 23 is rotated in the forward or reverse direction by the zooming motor 15, the cam ring 30 is moved in the optical axis direction relative to the second linear guide ring 25 (and an assembly of the second outer barrel 23 and the second helicoid ring 21), in accordance with the engagement between the female helicoid 25 b and the male helicoid 30 a.

[0061] A third linear guide ring 33 which is rotatable relative to, and is movable in, the optical axis direction together with the cam ring 30 (i.e., not movable in the optical axis direction relative to the cam ring 30) is supported in the cam ring 30. The third linear guide ring 33 is provided on the outer peripheral surface thereof with a plurality of linear guide projections 33 a which are engaged in a linear guide groove 25 d formed on the inner peripheral surface of the second linear guide ring 25, so that the third linear guide ring 33 is linearly movable only in the optical axis direction.

[0062] A lens support barrel (fourth outer barrel) 31 having a first variable power lens group L1 (first sub-lens group S1 and a second sub-lens group S2) and a second lens group frame 32 having a second variable power lens group L2 secured thereto are arranged in the cam ring 30. The lens support barrel 31 and the second lens group frame 32 are guided to linearly move in the optical axis direction with the third linear guide ring 33. Specifically, as shown in FIGS. 9 and 10, three arms 33 b, which are provided on the periphery of an imaginary cylinder and constitute the third linear guide ring 33, are each provided on the outer and inner surfaces (front and rear sides) thereof with linear guide grooves 33 c and 33 d which extend parallel with the optical axis O. Linear guide projections (not shown) provided on the inner peripheral surface of the lens support barrel 31 are movably fitted in the respective linear guide grooves 33 c, and linear guide projections 32 a provided on the outer peripheral surface of the second lens group frame 32 are movably fitted in the respective linear guide grooves 33 d.

[0063] The cam ring 30 is provided on the inner peripheral surface thereof with bottomed cam grooves 35 and bottomed cam grooves 36 for the lens support barrel 31 and the second lens group frame 32, respectively. FIG. 12 shows a developed view of the bottomed cam grooves 35 and 36. There are three sets of bottomed cam grooves 35 and 36, respectively, and are spaced in the circumferential direction at equal pitches. The lens support barrel 31 and the second lens group frame 32 are provided with radially extending cam follower projections 31 a and 32 b which are fitted in the bottomed cam grooves 35 and 36, respectively.

[0064] In FIG. 12, the bottomed cam grooves 35 and 36 have a range of usage between a telephoto extremity position and a retracted position. Upon photographing, the follower projections 31 a and 32 b are guided between the telephoto extremity position and a wide-angle extremity position within the range of usage of the bottomed cam grooves 35 and 36. The bottomed cam grooves 36 are each provided with an intermediate interruption portion 36 a between the telephoto extremity and the wide-angle extremity. The first variable power lens group L1 held in the lens support barrel 31 which is guided by the bottomed cam grooves 35 has a switching function to move the first sub-lens group S1 and the second sub-lens group S2 to a mutually close position and a mutually distant position at an intermediate position between the telephoto extremity and the wide-angle extremity. Upon switching of the first variable power lens group L1, the second variable power lens group L2 passes through the intermediate interruption portions 36 a of the bottomed cam grooves 36. The intermediate interruption portions 36 a are not used as zooming areas during an actual zooming operation (i.e., the cam ring 30 is not stopped thereat).

[0065] In the zoom lens barrel constructed as above, when the pinion 16 is rotated in the forward or reverse direction by the zooming motor 15, the cam ring 30 is moved in the optical axis direction while rotating, so that the lens support barrel 31 (first variable power lens group L1) and the second lens group frame 32 (second variable power lens group L2), guided in the cam ring 30 to linearly move in the optical axis direction, are linearly moved in the optical axis direction in accordance with predetermined profiles of the bottomed cam grooves 35 and 36. For instance, in the retracted position of the lens barrel (accommodated position) shown in FIG. 2, the entire zoom lens barrel is substantially retracted in the camera body. When the zooming motor 15 is driven in the barrel advancing direction, the zoom lens barrel is moved to the wide-angle extremity position shown in FIG. 3. The zoom lens barrel can be moved to the telephoto extremity position shown in FIG. 4 by further rotation of the zooming motor 15 in the barrel advancing direction. If the zooming motor 15 is rotated in the reverse direction, the zoom lens barrel is moved from the telephoto extremity position to the wide-angle extremity position and to the retracted position. The zooming operation is, in practice, controlled stepwise so that the focal length from the wide-angle extremity and the telephoto extremity is split into a plurality of focal length steps, wherein the zooming motor 15 is stopped at each focal length step to carry out focusing or an exposure. In the control therefor, the area corresponding to the switching of the first sub-lens group S1 and the second sub-lens group S2 between the mutually close position to the mutually distant position is not used for photographing and, hence, the focal length step does not exist in this area, wherein the cam ring 30 (zooming motor 15) does not stop thereat.

[0066] A lens-shutter unit 40 is provided in the lens support barrel 31. As shown in FIGS. 13 and 18, the lens-shutter unit 40 includes a front support ring 41, a rear support ring 42, a gear retainer ring 43 and a sector retainer ring 44. The lens-shutter unit 40 can be split into two units, i.e., a front unit 40A having an assembly including the front support ring 41 and the gear retainer ring 43, and a rear unit 40B having an assembly including the rear support ring 42 and the sector retainer ring 44.

[0067] The front unit 40A will be discussed below. The front support ring 41 has a center opening 41 a in which the front sub-lens group frame 45 and the rear sub-lens group frame 46 are fitted. The first sub-lens group S1 is secured to the front sub-lens group frame 45 and the second sub-lens group S2 is secured to the rear sub-lens group frame 46. The relative axial position of the front sub-lens group frame 45 and the rear sub-lens group frame 46 (the first sub-lens group S1 and the second sub-lens group S2) between the telephoto extremity and the wide-angle extremity can be selectively moved to the mutually distant position for a short focal length and the mutually close position for a long focal length. The relative movement of the axial position of the front sub-lens group frame 45 and the rear sub-lens group frame 46, and the focusing operation in which the front sub-lens group frame 45 and the rear sub-lens group frame 46 are moved together in the optical axis direction, can be performed by the drive ring 47.

[0068] The rearward extremity of the drive ring 47 is restricted by the receiving surface 42 s of the rear support ring 42 and is rotatably supported between the front support ring 41 and the rear support ring 42.

[0069] The front sub-lens group frame 45 is cylindrical and is provided on the outer periphery thereof with diametrically opposed linear guide ribs 45 a, as shown in FIG. 20. The linear guide ribs 45 a are provided with guide holes 45 b in which linear guide rods 48 are loosely fitted (inserted). The linear guide rods 48 are secured at the rear ends thereof to securing holes 43 a formed in the bottom of the gear retainer ring 43, and the front ends of the linear guide rods 48 are secured to a securing bracket 49. The securing bracket 49 is secured to the front surface of the gear retainer ring 43 with securing screws 50. Compression coil springs 51 which are provided between the securing bracket 49 and the linear guide ribs 45 a surround the linear guide rods 48 to bias the front sub-lens group frame 45 toward the rear sub-lens group frame 46. The gear retainer ring 43 is provided with generally U-shaped recesses 43 b in which the linear guide rods 48 and the compression coil springs 51 are received. The recesses 43 b are communicatively connected to the center opening 41 a of the front support ring 41.

[0070] The front sub-lens group frame 45 has four shift leading surfaces (shift cam surfaces) 45 c, which are formed circumferentially at equi-angular intervals on the end-face of the front sub-lens group frame 45, in order to move the front and rear sub-lens group frames to a mutually close position or a mutually distant position, in the optical axis direction. The shift leading surfaces 45 c are provided at their opposed ends with follower engaging recesses 45 d and 45 e (FIG. 22). Note that only one shift leading surface 45 c is shown in FIG. 22. The rear sub-lens group frame 46 is provided with four follower projections 46 a corresponding to the shift leading surfaces 45 c of the front sub-lens group frame 45. As shown in FIG. 20, the follower projections 46 a are provided on the front end portions of inclined surfaces 46 b, corresponding to the shift leading surfaces 45 c of the front sub-lens group frame 45. The shift leading surfaces 45 c formed on the front sub-lens group frame 45 and the follower projections 46 a formed on the rear sub-lens group frame 46 constitute a shift cam mechanism for moving the front sub-lens group frame 45 and the rear sub-lens group frame 46 to a mutually close position or to a mutually distant position, in the optical axis direction.

[0071] The rear sub-lens group frame 46 is also provided with a pair of linear guide projections 46 c which are located at the same circumferential positions as two of the four follower projections 46 a that are diametrically opposed, and are provided behind the two follower projections 46 a in the axial direction. Furthermore, three driven projections 46 d are provided on the outer peripheral surface of the rear sub-lens group frame 46 and are spaced at equi-angular intervals in the circumferential direction and behind the linear guide projections 46 c in the axial direction.

[0072] The front support ring 41 is provided on the inner peripheral surface thereof with a pair of rotation preventing surfaces 41 b and 41 c (see FIG. 22) which correspond to the linear guide projections 46 c of the rear sub-lens group frame 46 and restrict the angular displacement of the rear sub-lens group frame 46 with respect to the front support ring 41, which does no rotate. Namely, the rotation preventing surfaces 41 b and 41 c engage with the linear guide projections 46 c to prevent further rotation of the rear sub-lens group frame 46 at the rotational movement extremities thereof when the rear sub-lens group frame 46 is rotated in the forward and reverse directions. Moreover, the rotation preventing surface 41 b and the guide surface 41 d opposed thereto constitute a wide-angle linear guide groove 41 e, and the rotation preventing surface 41 c and the guide surface 41 f opposed thereto constitute a telephoto linear guide groove 41 g. The linear guide projections 46 c are substantially snugly engaged in the guide grooves 41 e and 41 g at the wide-angle and telephoto extremities, respectively.

[0073] The drive ring 47 has three control recesses 47 a (FIGS. 18 and 22) at the front end surface thereof, corresponding to the three driven projections 46 d of the rear sub-lens group frame 46. Note that only one or two control recesses 47 a are shown in the drawings. As shown in FIG. 23, the control recesses 47 a are symmetrical in the lateral direction with respect to a center line ‘c’ parallel with the optical axis, and each include a pair of effective surfaces 47 b and 47 c which engage with the driven projection 46 d, and telephoto and wide-angle focus leading surfaces (focus cam surfaces) 47 d and 47 e which abut against the arc end-surface of the driven projection 46 d. The telephoto focus leading surface 47 d and the wide-angle focus leading surface 47 e are defined by end cam surfaces having open ends between the effective surfaces 47 b and 47 c. The focus leading surfaces 47 d and 47 e are inclined with respect to the circumferential direction in opposite directions and at an equal inclination angle. The focus leading surfaces 47 d and 47 e of the drive ring 47 and the driven projections 46 d formed on the rear sub-lens group frame 46 constitute a focus cam mechanism.

[0074] The compression coil springs 51, which bias the front sub-lens group frame 45 rearwardly, cause the shift leading surfaces 45 c of the front sub-lens group frame 45 to be always in contact with the follower projections 46 a of the rear sub-lens group frame 46, and cause the driven projections 46 d of the rear sub-lens group frame 46 to be always in contact with the telephoto or wide-angle focus leading surfaces 47 d and 47 e. The drive ring 47 abuts at the rear end surface thereof against the receiving surface 42 s of the rear support ring 42, as mentioned above. The contact relationship of the front sub-lens group frame 45, the rear sub-lens group frame 46, the drive ring 47, and the rear support ring 42 (receiving surface 42 s) is maintained by the spring force of the compression coil springs 51. In contacting state, as shown in FIGS. 24 and 25, the front end of the rear sub-lens group frame 46 is inserted inside the inner peripheral surface of the front sub-lens group frame 45, and the drive ring 47 is fitted on the outer peripheral surface of the rear sub-lens group frame 46.

[0075] At the mutually distant position at the wide-angle side of the first sub-lens group S1 and the second sub-lens group S2, the effective surfaces 47 b of the drive ring 47 abut against the driven projections 46 d, and the linear guide projections 46 c are disengaged from the wide-angle linear guide grooves 41 e. In this state, if the drive ring 47 is moved in the right hand direction with respect to FIG. 22 (rotated in the clockwise direction), the effective surfaces 47 b press against the driven projections 46 d and rotate the rear sub-lens group frame 46 in the same direction, so that the linear guide projections 46 c abut against the rotation preventing surfaces 41 c. During this movement, the front sub-lens group frame 45 (first sub-lens group S1) comes close to the rear sub-lens group frame 46 (second sub-lens group S2) in accordance with the engagement of the shift leading surfaces 45 c and the follower projections 46 a of the rear sub-lens group frame 46 and, consequently, the follower projections 46 a are stably engaged in the follower engaging recesses 45 e.

[0076] Thus, the switching from the mutually distant position at the wide-angle side to the mutually close position at the telephoto side is completed. Consequently, the first sub-lens group S1 is close to the second sub-lens group S2 (mutually close extremity, i.e., at a mutually close position for a long focal length), and no further rotation of the drive ring 47 in the same direction is permitted.

[0077] When the switching to the mutually close position at the telephoto side is completed, the drive ring 47 is rotated in the reverse direction. Consequently, the driven projections 46 d (rear sub-lens group frame 46) are moved rearwardly in accordance with the telephoto focus leading surfaces 47 d and, hence, the linear guide projections 46 c are engaged in the telephoto linear guide grooves 41 g, so that the linear guide projections 46 c are linearly movable only in the axial direction. The focusing operation on the telephoto side, from an intermediate focal length to the long focal length extremity (telephoto extremity), is carried out by the integral movement of the rear sub-lens group frame 46 and the front sub-lens group frame 45 at the mutually close extremity via the telephoto focus leading surfaces 47 d. Namely, as shown in FIG. 23, when the drive ring 47 is rotated within the telephoto focus area ft (from the infinite object distance ∞ to the shortest object distance n) in a state that the driven projections 46 d of the rear sub-lens group frame 46 abut against the telephoto focus leading surfaces 47 d, the rear sub-lens group frame 46 whose rotation is restricted by the engagement of the telephoto linear guide grooves 41 g, the linear guide projections 46 c, and the front sub-lens group frame 45 whose rotation is restricted by the engagement of the linear guide rods 48 in the guide holes 45 b (i.e., the first sub-lens group S1 and the second sub-lens group S2) are integrally moved together in the optical axis direction to carry out the focusing operation.

[0078] When the drive ring 47 is rotated until the effective surfaces 47 c come into contact with the driven projections 46 d, the linear guide projections 46 c of the rear sub-lens group frame 46 are disengaged from the telephoto linear guide grooves 41 g. In this state, when the drive ring 47 is moved in the left hand direction in FIG. 22 (rotated in the counterclockwise direction), the effective surfaces 47 c press against the driven projections 46 d to thereby rotate the rear sub-lens group frame 46 in the same direction. Consequently, the linear guide projections 46 c abut against the rotation preventing surfaces 41 b. During this movement, the front sub-lens group frame 45 comes close to the rear sub-lens group frame 46 in accordance with the engagement of the shift leading surfaces 45 c and the follower projections 46 a of the rear sub-lens group frame 46, and the follower projections 46 a become stably engaged in the follower engaging recesses 45 d. Thus, the switching from the mutually close position at the telephoto side to the mutually distant position at the wide-angle side is completed, so that the first sub-lens group S1 moves away from the second sub-lens group S2 (mutually distant extremity, i.e., the mutually distant position for a long focal length), and no further rotation of the drive ring 47 in the same direction is permitted.

[0079] When the switching to the mutually distant position at the wide-angle side is completed, the drive ring 47 is rotated in the reverse direction. Consequently, the driven projections 46 d (rear sub-lens group frame 46) are moved rearwardly in accordance with the wide-angle linear guide grooves 41 e, and accordingly, the linear guide projections 46 c are engaged in the wide-angle linear guide grooves 41 e and is linearly movable only in the optical axis direction. The focusing operation on the wide-angle side, from an intermediate focal length to the short focal length extremity, is carried out by the integral movement of the rear sub-lens group frame 46 and the front sub-lens group frame 45 at the mutually distant extremity by the wide-angle linear guide grooves 41 e. Namely, as shown in FIG. 23, when the drive ring 47 is rotated within the wide-angle focus area fw (from the infinite object distance ∞ to the shortest object distance n) in a state that the driven projections 46 d abut against the wide-angle focus leading surface 47 e, the rear sub-lens group frame 46 whose rotation is restricted by the engagement of the wide-angle linear guide grooves 41 e and the linear guide projections 46 c, and the front sub-lens group frame 45 whose rotation is restricted by the engagement of the linear guide rods 48 in the guide holes 45 b (i.e., the first sub-lens group S1 and the second sub-lens group S2) are moved together in the optical axis direction to carry out the focusing operation.

[0080] When the drive ring 47 is rotated until the effective surfaces 47 b abut against the driven projections 46 d, the linear guide projections 46 c of the rear sub-lens group frame 46 are disengaged from the wide-angle linear guide grooves 41 e and are returned to the initial state.

[0081] As mentioned above, in the front unit 40A of the lens-shutter unit 40, the shifting operation for moving the first sub-lens group S1 and the second sub-lens group S2 to the mutually distant position for a short focal length, or to the mutually close position for a long focal length, and the focusing operation in which the first variable power lens group L1 is entirely moved in the optical axis direction, can be carried out by controlling the rotation of the drive ring 47. The focusing operations on the telephoto side and the wide-angle side are carried out by controlling the number of pulses counted by a pulser (encoder) of the driving system which drives the drive ring 47, with reference to the position (the position in which the direction of the rotation of the drive ring 47 is reversed) in which the linear guide projections 46 c of the rear sub-lens group frame 46 abut against the rotation preventing surfaces 41 b or 41 c. For instance, the number of the pulses to move the focusing lens group (i.e., the first variable power lens group L1 including the first sub-lens group S1 and the second sub-lens group S2) to the shortest object distance n, the infinite object distance ∞, or an object distance therebetween, from the reference position can be predetermined taking into account the lead angles of the telephoto and wide-angle focus leading surfaces 47 d and 47 e. Therefore, focusing can be carried out based on the object distance data by controlling the number of pulses.

[0082] The drive ring 47 is provided, on the entire outer peripheral surface of the rear end thereof, with a gear 47 f which is in mesh with a terminal gear 52 a (FIG. 18) of a reduction gear train 52, so that the gear 47 f can be rotated in the forward or reverse direction by a reversible drive motor 53 rotating in the forward and reverse directions (see FIGS. 13 and 18).

[0083] A pinion 53 a of the reversible drive motor 53 is located on the front side of the front support ring 41 and a gear 47 f of the drive ring 47 is located between the front support ring 41 and the rear support ring 42, i.e., on the rear side of the front support ring 41. Consequently, the reduction gear train 52, shown in FIG. 13, which transmits the motor drive force from the pinion 53 a to the gear 47 f, is held between the front support ring 41 and the gear retainer ring 43 in such a way that the gears are arranged along the outer peripheral surface of the front support ring 41. Moreover, a rotating slit disc 54, which constitutes the pulser to detect the amount of rotation of the reversible drive motor 53, is provided in the vicinity of the pinion 53 a of the reversible drive motor 53. A relay gear 55 is provided between the rotating slit disc 54 and the pinion 53 a.

[0084] The reversible drive motor 53 is held in a motor holding recess 41 h of the front support ring 41. The rotating slit disc 54 is held in the slit disc holding recess 41 i of the front support ring 41 (shown best in FIG. 17). The front support ring 41 is provided with an interrupter holding recess 41 j communicatively connected to the slit disc holding recess 41 i. A photo-interrupter 56 for detecting a drive amount of the reversible drive motor 53 for the switching operation of the sub-lens groups and for the focusing operation, is received in the interrupter holding recess 41 j (see FIG. 17). The rotating slit disc 54 is arranged in the photo-interrupter 56 (between two components of the photo-interrupter), so that the rotation angle (amount of angular displacement) of the slit disc 54 can be detected by counting the number of pulses. In other words, the drive amount of the reversible drive motor 53 can be detected.

[0085] The rear unit 40B will be explained below. A lens shutter and a diaphragm mechanism are provided between the rear support ring 42 and the sector retainer ring 44. As shown in FIGS. 13 and 14, the rear support ring 42 and the sector retainer ring 44 are provided with front wall portions 42 a and 44 a in the form of circular discs extending in orthogonal planes, with respect to the optical axis, and three rear arms 42 b and 44 b extending rearwardly in the optical axis direction from the front wall portions 42 a and 44 a, respectively. The lens shutter and the diaphragm mechanism are held between the front wall portions 42 a and 44 a. The rear arms 42 b and 44 b are overlapped in the radial direction of the lens barrel (see FIG. 15).

[0086] The lens shutter has three shutter sectors 60 and a shutter drive ring 61 which opens and closes the shutter sectors 60. The diaphragm mechanism has three diaphragm sectors 62 and a diaphragm drive ring 63 which opens and closes the diaphragm sectors 62. A separation plate 64 is arranged between the shutter sectors 60 and the diaphragm sectors 62, and a separation plate 65 is arranged between the diaphragm sectors 62 and the diaphragm drive ring 63. The separation plate 64 prevents interference between the movable shutter sectors 60 and the movable diaphragm sectors 62, and the separation plate 65 prevents interference of the diaphragm sectors 62 with the rotatable shutter drive ring 61 and the rotatable diaphragm drive ring 63. The sector retainer ring 44, the separation plate 64 and the separation plate 65 are provided with photographing circular openings 44 c, 64 a and 65 a, respectively, which have substantially in the same diameter about the optical axis O. The rear support ring 42 is provided with a center opening 42 c whose diameter is greater than the diameter of the photographing circular openings 44 c, 64 a and 65 a.

[0087] The shutter sectors 60 and diaphragm sectors 62 which are each made of three blades are rotatably supported by projecting pivots (support pivots) 66 (only one of which is shown in FIGS. 13 and 14) which extend rearward from the front wall portions 42 a of the rear support ring 42. The projecting pivots 66 extend through support holes 60 a and 62 a formed in the shutter sectors 60 and the diaphragm sectors 62. Projecting pivot securing holes 44 d (see FIG. 14), in which the front ends of the projecting pivots 66 are received, are formed in the front wall portions 44 a of the sector retainer ring 44.

[0088] The shutter drive ring 61 is provided with three rotation transmission dowels 61 a which are engaged in rotational guide cam slots 60 b formed in the shutter sectors 60. The three shutter sectors 60 are rotated about the projecting pivots 66 in accordance with the relationship between the rotational guide cam slots 60 b and the rotation transmission dowels 61 a when the shutter drive ring 61 is reciprocally rotated, so that the front portion of the photographing circular opening 44 c is opened and closed. The aperture of the shutter sectors 60 can be controlled by the angular displacement of the shutter drive ring 61. The sector retainer ring 44 is provided with dowel receiving slots 44 e in which the front ends of the rotation transmission dowels 61 a are inserted. The shutter drive ring 61 is biased in the closing direction by a shutter drive ring biasing spring 74, so that play (in the shutter drive ring 61) can be removed by the shutter drive ring biasing spring 74.

[0089] Similar to the shutter drive ring 61, the diaphragm drive ring 63 is provided with three rotation transmission dowels 63 a which are engaged in rotational guide cam slots 62 b formed in the diaphragm sectors 62. The three diaphragm sectors 62 are rotated about the projecting pivots 66 in accordance with the relationship between the rotational guide cam slots 62 b and the rotation transmission dowels 63 a when the diaphragm drive ring 63 is reciprocally rotated, so that the front portion of the photographing circular opening 44 c is opened and closed. The aperture of the diaphragm sectors 62 can be controlled by the angular displacement of the diaphragm drive ring 63. The diaphragm sectors 62 are provided with through-holes 62 c to prevent interference with the rotation transmission dowels 61 a of the shutter drive ring 61 regardless of the angular position of the diaphragm sectors 62. The front ends of the rotation transmission dowels 63 a are in contact with, and held by, the front surface of the front wall portion 44 a. The diaphragm drive ring 63 is biased by a diaphragm drive ring biasing spring 72 which is engaged at one end thereof with the diaphragm drive ring 63 and at the other end thereof with the rear support ring 42 in a direction to open the diaphragm sectors 62.

[0090] In the zoom lens barrel of the present invention, the shutter sectors 60 have a variable diaphragm function to determine a desired aperture value and a shutter function, and are electrically controlled so that the amount of opening (aperture value) and the opening time (shutter speed) of the shutter sectors 60 are varied in accordance with the exposure value when the shutter is released. The diaphragm sectors 62 are provided to restrict the maximum value of the aperture at a wide-angle object distance in particular, and the amount of opening thereof is varied in accordance with the feed amount of the zoom lens barrel as a whole.

[0091] The shutter drive ring 61 for opening and closing the shutter sectors 60 is provided on the outer peripheral surface thereof with a partial sector gear 61 b which is in mesh with a reduction gear train 68 connected to a shutter drive motor 67 (see FIGS. 13 and 18). The shutter drive motor 67 is held in a motor holding recess 41 k (see FIG. 17) of the front support ring 41, and a pinion 67 a of the shutter drive motor 67 is located in front of the front support ring 41. The reduction gear train 68 transmits the drive force of the motor to the rear side of the front support ring 41, and has a terminal gear 68 a distant from the pinion 67 a of the shutter drive motor 67 exposed to the rear portion of the front support ring 41 (front unit 40A), as shown in FIG. 18. The front wall portion 42 a of the rear support ring 42 is provided with a through-hole 42 e in which the terminal gear 68 a of the reduction gear train 68 is inserted so as to engage with the sector gear 61 b.

[0092] When the shutter drive motor 67 is rotated in the forward or reverse direction, the shutter drive ring 61 is rotated in the same direction, so that the shutter sectors 60, which are in a closed position, are instantaneously opened and closed. As mentioned above, the amount of opening, and the opening time of the shutter sectors 60 are variable and are controlled in accordance with the drive signal (electric current) supplied to the shutter drive motor 67. Namely, if the rotation angle of the shutter drive ring 61 driven by the shutter drive motor 67 is increased, the amount of opening of the shutter sectors 60 is increased and the aperture value is reduced (approaches a fully open diaphragm position). If the rotation angle of the shutter drive ring 61 is decreased, the amount of opening of the shutter sectors 60 is decreased and the aperture value is increased (diaphragm closes). Moreover, if the time interval between the forward rotation and the reverse rotation of the shutter drive ring 61 driven by the shutter drive motor 67 is shortened, the opening time of the shutter sectors 60 is shortened, so that the shutter speed is increased. Conversely, if the time interval between the forward rotation and the reverse rotation is lengthened, the opening time of the shutter sectors 60 is prolonged, thus resulting in a slower shutter speed.

[0093] The shutter drive ring 61 has a slit plate 61 c which is in the form of a small portion of a cylinder and protrudes forward in the optical axis direction. The slit plate 61 c extends through an arc opening 42 d (see FIG. 14), formed in the front wall portion 42 a of the rear support ring 42, and an arc opening 41 m (see FIG. 17) formed in the rear surface of the front support ring 41. The slit plate 61 c is located in a photo-interrupter 69 (between two components of the photo-interrupter 69) shown in FIG. 17, so that the passing of slits of the slit plate 61 c can be detected by the photo-interrupter 69 in order to detect the shutter operation. Namely, the opening and closing of the shutter sectors 60 can be detected by the operation of the shutter drive ring 61 via the slit plate 61 c and the photo-interrupter 69.

[0094] The front support ring 41 is provided with an interrupter holding recess 41 n (see FIG. 17) for receiving the photo-interrupter 69. The interrupter holding recess 41 n is located adjacent to the interrupter holding recess 41 j for receiving the photo-interrupter 56 for detecting the switching and focusing drive amount. The recesses 41 n and 41 j are covered by a common cover 70 in the form of a leaf spring. The two photo-interrupters 56 and 69 are held by the leaf spring cover 70.

[0095] As can be understood from the foregoing, in the zoom lens barrel of the present embodiment, the exposure is controlled by the shutter sectors 60. The purpose of the diaphragm sectors 62 is to restrict the size of the aperture so that the peripheral portion of the zoom lens system is not used for photographing at the short focal length.

[0096] The diaphragm drive ring 63, for opening and closing the diaphragm sectors 62, is provided on the outer peripheral surface thereof with a driven projection 63 b which is engaged in a diaphragm control cam groove 71 (see FIG. 10) formed in the inner peripheral surface of the arm 33 b of the third linear guide ring 33. Upon zooming, the third linear guide ring 33 and the lens-shutter unit 40 (diaphragm drive ring 63) are relatively moved in the optical axis direction. Consequently, the driven projection 63 b is moved in the circumferential direction in accordance with the diaphragm control cam groove 71 to rotate the diaphragm drive ring 63 to thereby vary the opening degree of the diaphragm sectors 62. As shown in FIG. 11, the diaphragm control cam groove 71 includes a linear restriction portion 71 a extending parallel with the optical axis O, an oblique restriction portion 71 b which is inclined with respect to the optical axis O, and a restriction releasing portion 71 c which opens into the front end of the third linear guide ring 33. The width of the linear restriction portion 71 a and the oblique restriction portion 71 b is such that the driven projection 63 b can be substantially snugly fitted therein.

[0097] When the zoom lens barrel is in the retracted position (accommodated position) shown in FIG. 2, the driven projection 63 b is located in the linear restriction portion 71 a. When the zoom lens barrel is advanced to the wide-angle position, the driven projection 63 b is still in the linear restriction portion 71 a. When the driven projection 63 b is in the linear restriction portion 71 a, the driven projection 63 b causes the aperture defined by the three diaphragm sectors 62 to be at a minimum aperture position. In the minimum aperture position, the diaphragm sectors 62 do not completely close the front portion of the photographing circular opening 44 c but cover a predetermined width of the peripheral portion of the circular opening in the radial direction. Consequently, photographing is carried out at the wide-angle extremity without collecting unnecessary light.

[0098] When the zoom lens barrel is advanced toward the telephoto side and reaches the fourth focal length step from the wide-angle extremity, the driven projection 63 b enters the oblique restriction portion 71 b from the linear restriction portion 71 a. The oblique restriction portion 71 b is inclined so that the diaphragm drive ring 63 is rotated in the diaphragm opening direction as the driven projection 63 b is moved toward the restriction releasing portion 71 c. Therefore, when the lens barrel is advanced while the driven projection 63 in located in the oblique restriction portion 71 b, the diaphragm drive ring 63 is rotated in the diaphragm opening direction to gradually open the diaphragm sectors 62. Specifically, a middle opening degree of the diaphragm sectors 62 is obtained at the fifth focal length step counting from the wide-angle extremity, and the diaphragm sectors 62 are fully opened at the sixth focal length step.

[0099] When further advancement of the zoom lens barrel takes place, the above-mentioned switching of the relative distance between the first sub-lens group S1 and the second sub-lens group S2 is carried between the sixth focal length step and the seventh focal length step, so that wide-angle photographing mode is transferred to the telephoto photographing mode. In the telephoto photographing mode, the driven projection 63 b is located in the restriction releasing portion 71 c. The restriction releasing portion 71 c is shaped so as to give less restriction on the relative position of the driven projection 63 b. When the driven projection 63 b is in the restriction releasing portion 71 c, the diaphragm drive ring 63 is held at an angle position to open the diaphragm sectors 62 by the diaphragm drive ring biasing spring 72. Therefore, in the telephoto photographing mode, a sufficient amount of light can be collected.

[0100] Conversely, when the zoom lens barrel is moved toward the wide-angle side from the telephoto side, the opening degree of the diaphragm sectors 62 is gradually reduced from the fifth focal length step counting from the wide-angle extremity. The diaphragm sectors 62 are closed in accordance with the relationship between the linear restriction portion 71 a and the driven projection 63 b, from the fourth focal length step to the wide-angle extremity (first focal length step). Note that the restriction releasing portion 71 c has an inclined guide surface 71 d which is adapted to smoothly guide the driven projection 63 b to the oblique restriction portion 71 b when the photographing mode is transferred from the telephoto photographing mode to the wide-angle photographing mode. The inclined guide surface 71 d ensures that the driven projection 63 b is moved into the oblique restriction portion 71 b without interfering with the diaphragm control cam groove 71, even if the angular position of the diaphragm drive ring 63 which has been released at the telephoto photographing mode is slightly out of alignment.

[0101] In the rear unit 40B constructed as above, the rotatable shutter drive ring 61 and the rotatable diaphragm drive ring 63 are located substantially in the same position in the axial direction. The shutter drive ring 61 is supported on the inner diameter side of the diaphragm drive ring 63 (see FIG. 15). The diaphragm drive ring 63 is provided on the inner peripheral surface thereof with three inner diameter thrust projections 63 c that are spaced in the circumferential direction at equi-angular intervals to rotatably support the shutter drive ring 61. The shutter drive ring 61 is provided on the outer peripheral surface thereof with three outer diameter thrust projections 61 d that are spaced in the circumferential direction at equi-angular intervals to engage with the inner diameter thrust projections 63 c. The diaphragm drive ring 63 is in contact with the rear surface of the front wall portion 42 a of the rear support ring 42 and the rotation transmission dowels 63 a are in contact with the front surface of the front wall portion 44 a of the sector retainer ring 44, so that the diaphragm drive ring 63 is supported between the rear support ring 42 and the sector retainer ring 44 so as not relatively move in the optical axis direction. The driven projection 63 b of the diaphragm drive ring 63 supported between the rear support ring 42 and the sector retainer ring 44 (between the front wall portion 42 a and the front wall portion 44 a) is located between a pair of rear arms 42 b and 44 b in the circumferential direction, so that the driven projection 63 b can be engaged by the diaphragm control cam groove 71 of the third linear guide ring 33 (see FIG. 10). The shutter drive ring 61 is supported between the rear support ring 42 and the sector retainer ring 44, with the shutter drive ring 61 in contact with the rear surface of the front wall portion 42 a and with the outer diameter thrust projections 61 d being engaged with the inner diameter thrust projections 63 c. The diaphragm drive ring 63 is shaped so that the sector gear 61 b (see FIGS. 24 and 25) of the shutter drive ring 61, located inside the diaphragm drive ring 63, can engage with the reduction gear train 68.

[0102] As can be understood from the above discussion, the lens-shutter unit 40 includes the front unit 40A having the first variable power lens group L1 (first sub-lens group S1 and second sub-lens group S2) and the drive mechanism therefore, and the rear unit 40B having the lens shutter and the diaphragm mechanism. The front unit 40A includes the reversible drive motor 53 for driving the first variable power lens group L1, and the shutter drive motor 67 for opening and closing the shutter sectors 60. The front unit 40A is also provided with the photo-interrupter 56 which detects the shift movement of the first sub-lens group S1 and the second sub-lens group S2 and the movement of the entire first variable power lens group L1 during the focusing operation, and the photo-interrupter 69 which detects the opening and closing operation of the shutter sectors 60. The reversible drive motor 53, the shutter drive motor 67, and the photo-interrupters 56 and 69 are connected to a control circuit 81 (see FIG. 2) in the camera body 11 via a lens-shutter unit FPC (flexible printed circuit) 80. As shown in FIGS. 13 and 16, the lens-shutter unit FPC 80 is divided into an annular FPC 80A extending around the outer peripheral surface of the front unit 40A, and a foldable strip FPC 80B which is elongated in the optical axis direction. The annular FPC 80A is double-sided FPC having circuit patterns printed on upper and lower surfaces thereof. The foldable strip FPC 80B is a one-sided FPC having a circuit pattern printed on only one of upper and lower surfaces thereof.

[0103] The foldable strip FPC 80B is secured at a shutter securing end 80B-1 to the front support ring 41 by a securing screw 82, as shown in FIG. 13. An FPC support plate 83 is inserted between the shutter securing end 80B-1 and the securing screw 82. A cylindrical press-contact support rubber 84 is inserted between the shutter securing end 80B-1 and the front support ring 41. As shown in FIGS. 2 and 4, the foldable strip FPC 80B is connected at the other end to the control circuit 81. The foldable strip FPC 80B can be freely deformed to vary the position of the bent portions and the linear portions thereof in accordance with the relative position of the lens-shutter unit 40 and the control circuit 81 which is changed in accordance with the advance or retraction of the zoom lens barrel, to prevent an interference of the FPC with other members of the lens barrel or the photographing light path. The foldable strip FPC 80B is not connected to the motors (reversible drive motor 53 and the shutter drive motor 67) or the photo-interrupters 56 and 69 when the foldable strip FPC 80B is solely mounted to the front support ring 41. Namely, the motors and the photo-interrupters are connected to the control circuit 81 when the annular FPC 80A is mounted.

[0104] As shown in FIG. 17, the annular FPC 80A has two motor terminals 80A-1 and 80A-2 to supply power to the reversible drive motor 53 and the shutter drive motor 67, and two interrupter terminals 80A-3 and 80A-4 to receive the pulses output from the photo-interrupters 56 and 69, respectively. The wiring conductors extending from the terminals are gathered at a press-contact portion 8OA-5. The press-contact portion 80A-5 is brought into press contact with the shutter securing end 80B-1 of the foldable strip FPC 80B, so that the wiring conductors of the annular FPC 80A and the foldable strip FPC 80B are connected. Thus, the reversible drive motor 53, the shutter drive motor 67, and the photo-interrupters 56 and 69 are electrically connected to the control circuit 81. The press-contact portion 80A-5 of the annular FPC 80A is fastened together with the shutter securing end 80B-1 of the foldable strip FPC 80B by the securing screw 82, and are secured to the front support ring 41. The annular FPC 80A is also provided with four positioning holes 80A-6 in which front surface projections 43 c (see FIGS. 20 and 21) of the gear retainer ring 43 are fitted to determine the position thereof.

[0105] The leaf spring cover 70, which holds the photo-interrupters 56 and 69, covers the portion of the annular FPC 80A hatched in FIG. 17 to stably hold the annular FPC 80A.

[0106] As shown in FIG. 26, the control circuit 81 controls the zooming motor 15 as well as the reversible motor 53 and the shutter drive motor 67. Focal length information 81A set by an operator (photographer) via a zoom switch (zoom operating device) etc., detected object distance information 81B, object brightness information 81C, angular position information of the cam ring 30 detected by a focal length detection device including the brush 19 and the code plate 20, focusing drive amount information (position switching information of the first sub-lens group S1 and the second sub-lens group S2) detected by the photo-interrupter 56, and opening and closing state information of the shutter sectors 60 detected by the photo-interrupter 69 are input to the control circuit 81. The zooming motor 15, the reversible drive motor 53, and the shutter drive motor 67 are controlled so that the exposure is carried out under the correct exposure conditions at the set focal length, based on the input information. Note that although, in the illustrated embodiment, the shutter sectors 60 function as a shutter and a variable diaphragm, and the diaphragm sectors 62 restrict the aperture size at the wide-angle photographing position, it is possible to use a variable diaphragm mechanism in which the diaphragm sectors 62 are electrically driven by a motor.

[0107] The lens-shutter unit 40 is assembled with the members discussed above into a unit which is incorporated in the lens support barrel 31. Namely, the front unit 40A and the rear nit 40B are assembled separately, the two units 40A and 40B are secured using three unit securing screws 39 (see FIG. 13), and the assembly of the units 40A and 40B is mounted into the lens support barrel 31.

[0108] As shown in FIG. 21, the rear support ring 42 of the lens-shutter unit 40 is provided with engagement projections 42 f provided on the outer surfaces of the three rear arms 42 b. The engagement projections 42 f are engaged in the engagement holes 31 c of the lens support barrel 31. The engagement projections 42 f are formed on resilient tongue portions 42 g which are elastically deformable in the radial directions. When the lens-shutter unit 40 is inserted in the direction indicated by an arrow in FIG. 21 into the lens support barrel 31, the engagement projections 42 f are moved inwardly by the inner surface of the lens support barrel 31, so that the elastic tongue portions 42 g are elastically deformed inwardly. Further insertion o the lens-shutter unit 40 causes the engagement projections 42 f to engage in the engagement holes 31 c, so that the elastic tongue portions 42 g are returned to the initial state, or the inward deformation of the elastic tongue portions 42 g is reduced. The cross sectional shape of the engagement projections 42 f is such that the elastic tongue portions 42 g can be easily deformed inwardly when the lens-shutter unit 40 is inserted forwardly in the optical axis direction, and the lens-shutter unit 40 cannot slip off the lens support barrel 31 in the rearward direction. Therefore, when the engagement projections 42 f engage in the engagement holes 31 c, the lens-shutter unit 40 is held in the lens support barrel 31. Three lens-shutter unit retainer springs 73 (see FIGS. 1 and 13) are provided between the lens-shutter unit 40 and the lens support barrel 31 to bias the lens-shutter unit 40 rearwardly in the optical axis direction. Accordingly, the axial position of the lens-shutter unit 40 can be accurately determined.

[0109] It is possible to adjust the position of the lens-shutter unit 40 in a direction perpendicular to the optical axis, during the assembly of the lens barrel. The lens support barrel 31 is provided on the inner peripheral surface thereof with a substantially annular front wall portion 31 b in the vicinity of the front end of the lens support barrel 31. The front wall portion 31 b is provided with an insertion hole 31 e (see FIG. 21) in which an eccentric member 85 and a direction member 86 are rotatably fitted. The eccentric member 85 is engaged in the gear retainer ring 43 of the lens-shutter unit 40. The eccentric member 85 and the direction member 86 are relatively rotatable. When the direction member 86 is rotated from the front end of the lens support barrel 31, the front end of the eccentric member 85 (the end of the eccentric member engaging with the lens-shutter unit 40) is moved in a plane perpendicular to the optical axis O. Consequently, the position of the lens-shutter unit 40 in the direction perpendicular to the optical axis within the lens support barrel 31 is varied, whereby the position of the first variable power lens group L1 supported by the lens-shutter unit can be adjusted.

[0110] The lens support barrel 31 is provided on the front end thereof with a lens barrier mechanism which opens and closes the front opening of the first variable power lens group L1. As shown in FIG. 1, the lens barrier mechanism has a barrier unit including an outer decorative plate 90 secured to the front end of the lens support barrel 31, a barrier retainer ring 96, a pair of outer barrier blades 92 and a pair of inner barrier blades 93which are rotatably mounted between the barrier retainer ring 96 and the decorative plate 90, and barrier springs 94. A barrier drive ring 91 is supported between the barrier unit and the front end 31 b of the lens support barrel 31 so as to be rotatable about the optical axis O. The decorative plate 90 is provided with a projection (not shown) which rotatably supports the outer and inner barrier blades 92 and 93. The outer and inner barrier blades 92 and 93 are rotated about this projection and are associated with each other to carry out the opening and closing operation. The barrier blades 92 and 93 are biased by the barrier springs 94 in a closing direction.

[0111] The barrier drive ring 91 is provided with diametrically opposed barrier engagement portions 91 a and a driven arm 91 b which extends rearwardly in the optical axis direction. The barrier engagement portions 91 a engage with the inner barrier blades 93 to transmit the rotation of the barrier drive ring 91 to the inner barrier blades 93. The inner barrier blades 93 are associated with the outer barrier blades 92, and hence, the rotation of the barrier drive ring 91 is transmitted to the outer barrier blades 92 via the inner barrier blades 93. The driven arm 91 b extends through a center opening 31 d of the front wall portion 31 b (see FIG. 21) into the lens support barrel 31. The driven arm 91 b can be engaged with an inclined guide surface 33 e formed on the front end of the partially cylindrical arm 33 b of the third linear guide ring 33.

[0112] The barrier drive ring 91 is biased by the drive ring biasing spring 95 in a direction to open the barrier blades 92 and 93. The drive ring biasing spring 95 is stronger than the barrier biasing spring 94, so that the biasing force of the drive ring biasing spring 95 is transmitted to the barrier blades 92 and 93 through the barrier engagement projections 91 a to thereby open the barrier blades 92 and 93 against the barrier spring 94 when the barrier drive ring 91 is in a free state. At the wide-angle extremity shown in FIG. 3 and at the telephoto extremity shown in FIG. 4, the driven arm 91 b and the inclined guide surface 33 e do not come into contact with each other, so that the barrier drive ring 91 is free and, hence, the barrier blades 92 and 93 are open (see FIG. 25). When the zoom lens barrel is moved from the wide-angle extremity to the retracted position shown in FIG. 2, the inclined guide surface 33 e of the third linear guide ring 33 engages with the driven arm 91 b of the barrier drive ring 91, so that the barrier drive ring 91 is forcedly rotated in a direction against the drive ring biasing spring 95, i.e., in a direction to permit the barrier blades 92 and 93 to be closed, in accordance with the shape of the inclined guide surface 33 e. Consequently, the barrier blades 92 and 93 which have been released from the restriction by the barrier drive ring 91 are closed by the spring force of the barrier spring 94 (see FIG. 24).

[0113] As mentioned above, in the zoom lens barrel of the present embodiment, the drive ring 47 is rotated to move the first variable power lens group L1 in the optical axis direction to carry out the focusing operation. As indicated by two-dotted chain line in FIG. 25, when the first variable power lens group L1 is moved to the front extremity of the movement for the focusing operation, the front end of the front sub-lens group frame 45 which supports the first sub-lens group S1 is moved to a position located more forward than the axial positions of the barrier blades 92 and 93. Note that FIG. 25 shows the telephoto photographing mode in which the first sub-lens group S1 and the second sub-lens group S2 are in the mutually close position. Likewise, at the wide-angle photographing mode in which the first sub-lens group S1 and the second sub-lens group S2 are in the mutually distant position, the front end of the front sub-lens group frame 45 is moved to a position located more forward than the axial positions of the barrier blades 92 and 93 at the front extremity of the movement for the focusing operation.

[0114] In the zoom lens barrel constructed as above, the shutter mechanism and the diaphragm mechanism are held between the rear support ring (support frame) 42 and the sector retainer ring (support frame) 44, of the rear unit 40B of the lens-shutter unit 40. Namely, each of the front wall portion 42 a of the rear support ring 42 and the front wall portion 44 a of the sector retainer ring 44 is a circular plate portion provided in a plane normal to the optical axis, and the three shutter sectors (shutter member) 60 and the three diaphragm sectors (diaphragm member) 62 are rotatably supported by the projecting pivots 66 between opposed surfaces of the front wall portion 42 a and the front wall portion 44 a. Also, the shutter drive ring (inner drive ring) 61 and the diaphragm drive ring (outer drive ring) 63 are coaxially supported to rotate about the optical axis O between opposed surfaces of the front wall portion 42 a and the front wall portion 44 a. As mentioned above, when the shutter drive ring 61 is rotated in the forward and reverse direction, the three shutter sectors 60 are opened and closed. If the diaphragm drive ring 63 is rotated in the forward and reverse direction, the aperture diameter of the three diaphragm sectors 62 can be varied.

[0115] As can be seen in FIG. 27 which shows a sectional view of the rear unit 40B in a position different from FIG. 15, the rear unit 40B includes an opening 40B-s which extends radially, and is formed between the rear support ring 42 and the sector retainer ring 44 (between front wall portion 42 a and the front wall portion 44 a) and between each of the three rear arms 42 b (and 44 b) in a circumferential direction. The sector retainer ring 44 has overhang portions (outer peripheral wall portions) 44 f which project forwardly in the optical axis direction from the outer peripheral edge of the front wall portion 44 a and partly cover the opening 40B-s (see FIGS. 14 and 27).

[0116] As shown in FIGS. 15 and 27, the shutter drive ring 61 and the diaphragm drive ring 63 are located substantially at the same position in the axial direction and at different positions in the radial direction, i.e., so as to overlap each other in the radial direction. The diaphragm drive ring 63 is located more outwardly in the radial direction than the shutter drive ring 61.

[0117] The diaphragm drive ring 63 is provided on the outer peripheral surface thereof with stepped portions 63 d (see FIG. 27) and fitting portions 63 e that extend radially and outwardly from the stepped portions 63 d. The stepped portions 63 d overlap the overhang portions 44 f in the radial direction and engage with the inner surfaces of the overhang portions 44 f. The fitting portions 63 e are inserted in a space (opening 40B-s) defined between the front ends of the overhang portion 44 f and the front wall portion 42 a, and are located between the front surfaces of the overhang portions 44 f and the rear surface of the front wall portion 42 a. The outward and radial position of the diaphragm drive ring 63 is restricted by the engagement of the stepped portions 63 d and the overhang portions 44 f. Furthermore, the axial position of the diaphragm drive ring 63 is restricted when the fitting portions 63 e are supported between the overhang portions 44 f and the front wall portion 42 a. The main body of the diaphragm drive ring 63 contacts with the rear surface of the front wall portion 42 a of the rear support ring 42, and the front ends of the rotation transmission dowels 63 a contact with the front surface of the front wall portion 44 a of the sector retainer ring 44. The axial position of the diaphragm drive ring 63 is also restricted by the engagement of the main body of the drive ring 63 and the rotation transmission dowels 63 a with the front wall portions 42 a and 44 a, respectively.

[0118] The shutter drive ring 61 is supported at the main body thereof by a stepped portion 42 h, formed on the rear surface of the front wall portion 42 a of the rear support ring 42, and a small diameter cylindrical portion 42 i projecting rearwardly in the axial direction from the front wall portion 42 a, so that the position of the shutter drive ring is restricted in the forward axial direction and in the radial direction. The position of the shutter drive ring 61 in the axial and rearward direction is restricted by the engagement of the outer diameter thrust projections (outer flange) 61 d and the inner diameter thrust projections (inner flange) 63 c provided on the diaphragm drive ring 63.

[0119] The outer diameter thrust projections 61 d and the inner diameter thrust projections 63 c engage and overlap each other in the axial direction (optical axis direction) of the drive rings 61 and 63, so that they are not relatively movable in the axial direction but are relatively slidable in the circumferential direction. The shutter drive ring 61, which is located more inwardly than the diaphragm drive ring 63, and the diaphragm drive ring 63 are coaxially rotatable relative to each other by the sliding contact between the outer diameter thrust projections 61 d and the inner diameter thrust projections 63 c. Namely, the rotating support structure of the shutter drive ring 61 is partly formed by the diaphragm drive ring 63, and the rotating support structure of the diaphragm drive ring 63 is partly formed by the shutter drive ring 61, respectively. In particular, the position of the shutter drive ring 61 in the optical axis direction is determined by the engagement of the outer diameter thrust projections 61 d and the inner diameter thrust projections 63 c.

[0120] The driven projection 63 b of the diaphragm drive ring 63 supported as described above is provided on the fitting portion 63 e and extends from the opening 40B-s in the radial and outward direction, so that the driven projection 63 b can be actuated from the outside of the rear unit 40B (FIG. 10). The driven projection 63 b is engaged in the diaphragm control cam groove (rotational force providing device) 71 of the third linear movement guide ring 33, so that the diaphragm drive ring 63 can be rotated via the engagement between the diaphragm control cam groove 71 and the driven projection 63 b in accordance with the zooming operation.

[0121] The sector gear 61 b of the shutter drive ring 61 is in mesh with the terminal gear 68 a (see FIG. 18), of the reduction gear train (motor drive gear) 68, which projects toward the rear surface of the front wall portion 42 a, so that the drive force of the shutter drive motor 67 is transmitted to the shutter drive ring 61. The diaphragm drive ring 63 is provided on the inner peripheral surface thereof with a cut-away portion 63 f (radial space) to prevent interference with the end gear of the reduction gear train 68 (see FIG. 14).

[0122] In the structure of the rear unit 40B, the rotating support structure of the shutter drive ring and the diaphragm drive ring can be simplified. Namely, two drive rings, i.e., the shutter drive ring 61 and the diaphragm drive ring 63 are provided in the rear unit 40B, however, the rotating support structure on the rear support ring 42 side or the sector retainer ring 44 side can be simplified because the shutter drive ring 61 and the diaphragm drive ring 63 overlap in the radial direction (i.e., are located at different positions in the radial direction) and the outer and inner diameter thrust projections 61 d and 63 c of the drive rings 61 and 63 which are opposed in the radial direction engage with each other, so that one of the drive rings 61 and 63 forms the rotating support structure of the other drive ring. Namely, it is necessary for the rear support ring 42 and the sector retainer ring 44 to restrict the radial positions of the drive rings 61 and 63, and restrict the axial position of only one of the drive rings 61 and 63. Consequently, no individual rotating supports for the rear support ring 42 and the sector retainer ring 44 are necessary, and thus the rear unit 40B, and accordingly the lens-shutter unit 40, can be made compact.

[0123] The rear unit 40B is provided on the outer peripheral portion thereof with the opening 40B-s, through which the driven projection 63 b of the diaphragm drive ring 63 extends outwardly. Therefore, it is necessary to prevent harmful light, which does not pass through the photographing circular opening (photographing aperture) 44 c, from leaking from, e.g., the inner diameter side (center opening (photographing aperture) 42 c) to the outer diameter side (opening 40B-s) of the rear unit 40B. In the lens shutter mechanism, such harmful light which would otherwise pass through the opening 40B-s in the rear unit 40B can be effectively interrupted. Namely, since the shutter drive ring 61 and the diaphragm drive ring 63 are arranged in an overlapped state in the radial direction within a space through which the harmful light passes, it is difficult for harmful light to travel linearly therethrough. Furthermore, since the opening 40B-s is covered by the overhang portions 44 f and the diaphragm drive ring 63 (fitting portions 63 e) which partly overlaps the overhang portions 44 f, harmful light, which is not intercepted by the body portions of the shutter drive ring 61 and the diaphragm drive ring 63 and travels in the radial and outward direction, can be certainly intercepted. The overhang portions 44 f and the fitting portions 63 e engage with each other and form the rotating support structure of the diaphragm drive ring 63. Namely, a plurality of functions including the light interception function can be provided.

[0124] Therefore, no troublesome operation in attaching light interception tapes to the outer periphery of the rear unit 40B is necessary, and thus, the light interception structure can be simplified. Furthermore, there is no chance that the movable members in the rear unit 40B are interfered with light interception tapes, since light interception tapes are not necessary. Note that the opening 40B-s is not formed at the portions of the rear support ring 42 and sector retainer ring 44 on which the rear arms 42 b and 44 b are provided since light interception thereat is performed by the rear arms 42 b (FIG. 15).

[0125] As can be understood from the above discussion, according to the present invention, a small and simple lens shutter mechanism in which the surrounding components of the shutter can be reliably intercepted from harmful light can be attained. Namely, the arrangement of the shutter drive ring 61 and the diaphragm drive ring 63 is provided, so that the drive rings 61 and 63 have plural functions including the rotating support function thereof and the light interception function of the lens-shutter unit 40, and hence, the lens-shutter unit 40 can be manufactured with less number of elements and can be made simple and compact. Moreover, since the drive rings, i.e., the movable members, constitute a portion of the light interception mechanism, there is no chance of the rotation of the shutter and diaphragm drive rings 61 and 63 being interrupted by other light interception members such as the light interception tapes, and thus, the shutter and the diaphragm can be reliably driven.

[0126] The present invention is not limited to the illustrated embodiments. For instance, the shutter sectors 60 have a variable stop function for the exposure control and the diaphragm sectors 62 restrict the aperture diameter on the wide-angle side in the illustrated embodiments. However, the present invention can be equally applied to a lens shutter mechanism in which the diaphragm sectors have a variable stop function to optionally vary the aperture value and the shutter sectors only have the shutter function.

[0127] Although the diaphragm drive ring 63 is located outside the shutter drive ring 61 to expose the driven projection 63 b to the outer peripheral of the lens-shutter unit 40 in the illustrated embodiments, the positional relationship between the shutter drive ring and the diaphragm drive ring in the radial direction can be opposite if the drive mechanism to rotate the drive rings is different from that of the illustrated embodiments. For example, if both the shutter drive ring and the diaphragm drive ring are driven by a motor incorporated in the lens-shutter unit, it is possible to arrange the shutter drive ring on the outer side of the periphery of the diaphragm drive ring.

[0128] Obvious changes may be made in the specific embodiment of the present invention described herein, such modifications being within the spirit and scope of the invention claimed. It is indicated that all matter contained herein is illustrative and does not limit the scope of the present invention. 

What is claimed is:
 1. A lens shutter mechanism provided between front and rear support frames spaced in an optical axis direction and having photographing apertures, said lens shutter mechanism comprising: shutter sectors which open and close said photographing apertures; a shutter drive ring which is rotatable about the optical axis to drive said shutter sectors; diaphragm sectors which change an aperture diameter of said photographing apertures independently of said shutter sectors; and a diaphragm drive ring which is rotatable about the optical axis to drive said diaphragm sectors; wherein said shutter drive ring and said diaphragm drive ring are located at different radial positions and at the same position in the optical axis direction; and wherein one and the other of said shutter drive ring and said diaphragm drive ring is provided with an inner flange and an outer flange respectively, said inner flange and said outer flange projecting in a radial direction toward each other so as to overlap in the axial direction, and engaging so as to be relatively slidable in the circumferential direction.
 2. The lens shutter mechanism according to claim 1, wherein an axial position of one of said shutter drive ring and diaphragm drive ring is determined in accordance with an engagement thereof with said front and rear support frames; and wherein an axial position of the other of said shutter drive ring and diaphragm drive ring is determined in accordance with an engagement thereof with one of said front and rear support frames and in accordance with an engagement thereof between said inner flange and said outer flange.
 3. The lens shutter mechanism according to claim 1, further comprising an opening between said front and rear support frames, which extends form the inner diameter side to the outer diameter side of said front and rear support frames; and wherein one of said shutter drive ring and said diaphragm drive ring, which is positioned at an outer radial position with respect to the other of said shutter drive ring and said diaphragm drive ring, is provided with a fitting portion which is fitted in said opening in order to cover said opening, said fitting portion being movable in the circumferential direction.
 4. The lens shutter mechanism according to claim 3, wherein one of said front and rear support frames is provided on the outer peripheral edge thereof with an outer peripheral wall portion which projects in the optical axis direction close to the other of said front and rear support frames; wherein said one of said shutter drive ring and said diaphragm drive ring, having said fitting portion, partly overlaps said outer peripheral wall portion in the radial direction to cover said opening together with said outer peripheral wall portion.
 5. The lens shutter mechanism according to claim 3, further comprising: a driven projection provided on said fitting portion of said one of said shutter drive ring and said diaphragm drive ring, said driven projection extending outwardly from said opening in the radial direction; and a rotational force providing device provided outside said front and rear support frames, which engages with said driven projection to cause said one of said shutter drive ring and said diaphragm drive ring to rotate.
 6. The lens shutter mechanism according to claim 5, wherein said lens shutter mechanism is provided in a zoom lens, and wherein said rotational force providing device provides rotation to said driven projection in accordance with a zooming operation of said zoom lens to thereby rotate said one of said shutter drive ring and said diaphragm drive ring which includes said driven projection.
 7. The lens shutter mechanism according to claim 1, wherein one of said front and rear support frames is provided with a motor drive gear which projects from a surface thereof opposed to the other of said front and rear support frames, said motor drive gear being driven by a motor; wherein the other of said shutter drive ring and said diaphragm shutter drive ring, which is positioned at an inner radial position, is provided on the outer peripheral surface thereof with a gear which engages with said motor drive gear; and wherein a radial space in which said motor drive gear is accommodated is provided between said shutter drive ring and said diaphragm drive ring.
 8. The lens shutter mechanism according to claim 7, wherein said motor is controlled by a controller, to change the angular displacement and the rotation speed of said drive ring having said gear which engages with said motor drive gear.
 9. The lens shutter mechanism according to claim 1, wherein said diaphragm drive ring is located at an outer radial position with respect to said shutter drive ring, said diaphragm drive ring being provided with said inner flange on an inner peripheral surface thereof, and said shutter drive ring being provided with said outer flange on an outer peripheral surface thereof.
 10. A lens shutter mechanism comprising, between front and rear support frames spaced in an optical axis direction and having photographing apertures: shutter sectors which open and close the photographing apertures; a shutter drive ring which is rotated about the optical axis to drive said shutter sectors; diaphragm sectors which change an aperture diameter of the photographing apertures independently of said shutter sectors; and a diaphragm drive ring which is rotated about the optical axis to drive said diaphragm sectors; wherein said shutter drive ring and said diaphragm drive ring are located at different radial positions and at the same position in the optical axis direction, so that said shutter drive ring is located at an inner radial position and said diaphragm drive ring is located at an outer radial position; and wherein said diaphragm drive ring is provided with an inner flange which projects inwardly in the radial direction, and said shutter drive ring is provided with an outer flange which projects outwardly in the radial direction, said inner flange and said outer flange overlapping in the axial direction and engaging so as to be relatively slidable in the circumferential direction.
 11. The lens shutter mechanism according to claim 10, wherein an axial position of said diaphragm drive ring is determined in accordance with an engagement thereof with said front and rear support frames; and wherein an axial position of said shutter drive ring is determined in accordance with an engagement thereof with one of the front and rear support frames and in accordance with an engagement thereof between said inner flange and said outer flange.
 12. The lens shutter mechanism according to claim 10, further comprising an opening between the front and rear support frames, which extends form the inner diameter side to the outer diameter side of said front and rear support frames; and wherein said diaphragm drive ring is provided with a fitting portion which is fitted in said opening in order to cover the opening, said fitting portion being movable in the circumferential direction.
 13. The lens shutter mechanism according to claim 12, wherein one of said front and rear support frames is provided on the outer peripheral edge thereof with an outer peripheral wall portion which projects in the optical axis direction close to the other of said front and rear support frames; wherein said diaphragm drive ring partly overlaps said outer peripheral wall portion in the radial direction to cover said opening together with said outer peripheral wall portion.
 14. The lens shutter mechanism according to claim 12, further comprising: a driven projection provided on said fitting portion of said diaphragm drive ring, said driven projection extending outwardly from said opening in a radial direction; and a rotational force providing device provided outside said front and rear support frames, which engages with said driven projection to cause said diaphragm drive ring to rotate.
 15. The lens shutter mechanism according to claim 14, wherein said lens shutter mechanism is provided in a zoom lens, and wherein said rotational force providing device provides rotation to the driven projection in accordance with a zooming operation of the zoom lens to thereby rotate said diaphragm drive ring.
 16. The lens shutter mechanism according to claim 10, wherein one of said front and rear support frames is provided with a motor drive gear which projects from a surface thereof opposed to the other of said front and rear support frames, said motor drive gear being driven by a motor; wherein said shutter drive ring is provided on the outer peripheral surface thereof with a gear which engages with said motor drive gear; and wherein a radial space in which said motor drive gear is accommodated is provided between said shutter drive ring and said diaphragm drive ring.
 17. The lens shutter mechanism according to claim 16, wherein said motor is controlled by a controller, to change the angular displacement and the rotation speed of said shutter drive ring. 